Apparatus of hydraulic backward stop system for gas duct line



y 6, 1970 MOTOAKI HIRAO 3,513,870

APPARATUS OF HYDRAULIC BACKWARD STOP SYSTEM FOR GAS DUCT LINE Filed May 13, 1968 INVENTOR MOTOAKI HIRAO ATTORNEYS United States Patent 3,513,870 APPARATUS OF HYDRAULIC BACKWARD STOP SYSTEM FOR GAS DUCT LINE Motoaki Hirao, Kobe-shi, Japan, assignor to Kawasaki Jukogyo Kabushiki Kaisha, Kobe, Japan Filed May 13, 1968, Ser. No. 728,550 Int. Cl. F16k 9/00 US. Cl. 137-251 2 Claims ABSTRACT OF THE DISCLOSURE A hydraulic backward flow stop device arranged in a gas delivery duct and includes a gas blast tube movably supported within the device by float members. The gas blast tube forms a gas tight seal with the delivery duct by having its upper top immersed in a water filled sleeve arranged about the discharge end of the delivery duct. The float members cause the gas blast tube to ascend and descend in relation to the level of water in one of the chambers in the device. The lower end of the gas blast tube is thereby maintained beneath the level of water in both chambers in the device due to the ascending and descending motion of the tube and the pressure differential between the chambers.

storing apparatus which includes a hydraulic backward stop system best suited to be arranged at the entrance of a gas holder.

Prior art It is well-known that when exhaust gas of an oxygen top-blown converter is recovered after cooling and dust removing, CO gas of 75-80 percent grade which can be efficiently utilized as fuel or chemical material can be obtained.

As is generally known, blow refining time in converter steel manufacture is usually about 20-30 minutes. The charging operation of molten pig iron, submaterials, etc. and steel tapping operations are respectively made before and after refining and therefore refining is repeated making a period of -50 minutes for one cycle.

Devices of this general type comprising a gas duct thrusted into the water where the blowing off of gas occurs have hitherto been used as hydraulic backward stop systems for low pressure gas duct systems. These prior art devices have faults as stated hereinafter and they are especially inconvenient in systems where amounts of gas produced are massive as in the amount of exhaust gas of the oxygen converter.

For example, in prior art devices the water level exposed to the storage chamber duct within theinterior of the hydraulic backward stop system rises when gas begins to pass through the entrance duct leading into the hydraulic back stop and consequently circulation resistance increases. It is, therefore, necessary to enlarge the area of water surface exposed to storage chamber entrance duct in order to check the rise of the water level. When the passing of gas stops, the Water level exposed to the storage chamber duct descends, while the water level exposed to the gas entering duct rises, and the counter flow is prevented. This arrangement, however, requires large areas of water surface being exposed to the storage chamber duct, and, consequently, large amounts of water are required to prevent the water seal being broken because of the excessive descent of water level exposed to the storage chamber duct.

In short, the prior art devices have the undesirable feature of the larger the flow rate of gas or size of the gas 3,513,870 Patented May 26, 1970 duct, the greater size of the hydraulic backward stop system is required. This is necessary because the area of water surface thereof must be fairly enlarged in order to make fluctuations of water level exposed to the storage chamber as small as possible.

SUMMARY OF THE INVENTION The present invention aims at eliminating such defects. It comprises the apparatus of the hydraulic backward stop system comprising a gas blast tube which is able to rise and fall and thereby keep proper relative relation with water level in water tank exposed to the storage chamber duct. The blast tube is fitted so as to be gas tight at the top end of he gas entering duct of the fixed type.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of a principal part system of an apparatus for disposing of exhaust gas of an oxygen convertenapplying the present invention;

FIG. 2 is a detailed drawing of an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, gas intermittently discharged from the converter (not shown) is released into the atmosphere through a release duct 2. Alternately, the gas may be recovered, by selective change of change-over valves 4 provided in a gas duct 3 on the discharge side of an induced draft fan 1. When a high percentage of CO gas, which is under increased pressure, is contained in the exhaust gas, it is delivered to a gas storage chamber 7 and stored.

During the recovery of gas in a system, a communicating duct line system may be used. The duct line may include controlling devices such as a blower 5, for increasing pressure, change-over valves 4, and a flow rate adjusting valve 9. These devices sometimes get out of order, and if the exhaust gas recovered happens to flow backward from the gas storage chamber 7, great danger is presented to the operator of the converter. The safest way to prevent this danger is to fit a hydraulic backward stop device 6 of the type of the present invention at the entrance of the gas holder 7.

In the embodiment of the hydraulic backward stop system shown in FIG. 2, a water tank 11 has a water tight housing lid 11' connected with a duct 3' communicating with the storage chamber 7. The gas inlet duct 3 is fixedly mounted and the end of it passes through lid 11' and opens to the inside of the hydraulic backward seal arrangement. The end of gas blast tube or annular member 10 is fitted air tight and is capable of free ascent and descent through water seal sleeve 13 which is arranged around the outside peripheral surface of the end of duct 3. The lower end of member 10 extends into the water within tank 11 to a suitable depth. The interior of the hydraulic backward stop apparatus body communicates with the gas entering duct 3 and is thus separated in two chambers. Chamber A is defined by the gas blast tube or member 10 and water surface and chamber B is defined by the lid body 11', the outer surface if the gas blast tube 10, the gas entrance duct 3 and watersurface. Floats 12 are buoyant on the water surface in the chamber B and are fixed in position to the gas blast tube 10 by supporting member 10'. Splash-boards 14 serve as a breakwater for the floats 12.

When gas flows into the chamber A from the gas inlet duct 3, the water level inside the chamber A descends due to the pressure directed against the Water. At the same time, the water level in chamber B rises. However, as mentioned above, since the gas blast tube 10 is mounted air tight and capable of free ascent and descent through water seal sleeves 13, the blast tube 10 ascends the same amount as the level in chamber B due to both the buoyancy of floats 12 and difference of internal pressures between the chamber A and the chamber B. The depth of water at the edge of the lower end of the blast tube 10 is thereby kept to a proper preestablished value without great fluctuation.

Accordingly, gas flowing into chamber A travels continuously through the water below chamber A to a depth established from circumference of the lower end of the blast tube 10. This gas then issues from the surface of the water in chamber B in the form of bubbles into the chamber B and is sent to the gas storage chamber 7 through the duct 3.

When inflow of gas stops, the pressure inside the chamher A falls and the water level inside the chamber B descends, causing the water level inside the chamber A to rise. Since in this case the blast tube 10 descends likewise by action of floats 12 there is no fear that the water seal is broken however low the water level in chamber B may descend.

Further, the upsetting or agitating of floats 12 is prevented by means of splash-boards 14 serving as a breakwater against the influence of disturbances and serving as a surface inside the chamber B which stops rocking and splashing due to the traveling of gas, and bubbles passing through the water. Consequently, floats 12 and the gas blast tube 10 always maintain a stable level position as required. Consideration must be given so that a water supply may always be made to the water seal tanks of water seal sleeve 13 necessary to allow the gas blast tube 10 to be able to maintain a gas tight fitting against the gas which is entering through duct 3 and therefore maintain the water seal.

It will be obvious to those skilled in the art that the same effect would be accomplished in the case where the gas entering duct 3 and the gas blast tube 10 are coupled with an expansion pipe made of elastic material, for example, rubber or with metallic bellows instead of using water seal sleeve 13. This, of course, is included in the scope of the present invention.

Consequently, according to the present invention, the water level in the water tank 11 may change, since the gas blast tube 10 ascends or descends in accordance with the change. As a result, the circumference of the lower end of tube 10 is always maintained to a suitable depth of water, even though the amount of water in the apparatus of the hydraulic backward stop system may diminish or fall to an excessive degree. Therefore, the water seal preventing counter current flow can be maintained and the passing resistance of the gas, based on excessive ascent of water level when circulating the gas, can be restricted to a minimum.

Therefore, in comparison with hitherto well-known apparatus of this type, a very small-sized apparatus can perform hydraulic check flow action safely and also for any gas duct line which has a large fiow rate or a large size. In addition, the performance of the hydraulic check flow apparatus is accurate and stable, and the cost of such equipment is reduced.

What is claimed is:

1. A hydraulic backward flow stop apparatus of the type utilized in a gas delivery duct leading from a gas supply means to a gas storage chamber comprising: an enclosed liquid holding tank adapted to be partially filled with a suitable liquid, said tank having an upper surface, gas inlet means and gas outlet means being provided in said upper surface, said gas inlet means comprising a duct having a vertical axis extending into said tank to a point above the surface of the liquid in said tank, gas blast tube means concentric with said duct and vertically slidable thereon, gas seal means between said duct and said tube means, said tube means having a lower end adapted to be disposed below the surface of the liquid in said tank, float means secured to said tube for maintaining said lower end of said tube a predetermined distance beneath the surface of the liquid in said tank to maintain a seal preventing the backward flow of gas from said storage chamber to said duct in spite of changes in the level of the liquid within said tank.

2. A hydraulic backward flow stop apparatus as set forth in claim 1 wherein said gas seal means is a liquid seal.

References Cited FOREIGN PATENTS 9,344 1899 Great Britain.

HAROLD W. WEAKLEY, Primary Examiner US Cl. X.R. 137247.35 

